Science —

Carbon Math 101: Why most of us flunk

If MIT graduate students don't understand the simple ins-and-outs of …

Public awareness of climate change has grown rapidly in the past few years, almost as quickly as atmospheric carbon dioxide has risen in the last 50. Many in the United States and other countries feel global warming poses a serious threat, but few seem willing to push for new policy to reduce carbon emissions. The phenomenon’s less-than-tangible effects may be at fault, but new research suggests the disconnect at the root of this reluctance may be even simpler than that.

Despite the press (and now marketing) focused on climate change, a 2007 survey in the US found that 54 percent of respondents favored "wait-and-see" or "go slow" approaches to the problem. Those numbers were even higher in Russia, China, and India.

To understand why many of the people who accept the severity of the problem still advocate restraint, John Sterman of the Massachusetts Institute of Technology’s Sloan School of Management gave 212 MIT graduate students the latest scientific findings (PDF), an unfinished graph of carbon emissions (complete with a dot representing “carbon neutral”), and a pencil. All 212 students were asked to extrapolate the emissions graph in a way that would ensure atmospheric carbon dioxide would level off by 2050. Fully 84 percent of them failed.

The shocking results, Sterman asserts in a paper published Thursday in the journal Science, stem from a misunderstanding of the principles of accumulation. To stabilize atmospheric carbon dioxide levels, the emissions spewing into the air must be offset by an equivalent amount of carbon leaving the system. This concept, he said, is best understood by envisioning a bathtub filling with water. If water from the faucet is rushing into the tub more rapidly than it is draining out, the tub will continue to fill. And if you don’t turn down the tap, the tub is eventually going to overflow.

Yet nearly two-thirds of the surveyed students argued that simply plateauing—not reducing—emissions will stabilize atmospheric carbon dioxide. The idea, he said, is "analogous to arguing a bathtub continuously filled faster than it drains will never overflow."

And these participants aren’t your average Joe the Plumber. They’re graduate students at MIT, and over half of them have degrees in science, mathematics, engineering, or technology. Nearly one-third already have graduate degrees. That's not to say that Joe the Plumber is lacking up top, but it emphasizes that even the smartest people in the nation misunderstand the concept.

Sterman believes more outreach and education are necessary before people will recognize any need for urgent action. If climate scientists partner with social scientists, he said, they can boost scientific understanding among both policy makers and the general public. That would be a welcome, not to mention necessary, step toward solving climate problems.